Le Thanh Liem

In this study, MnCo ₂ O ₄ is successfully synthesized via a one-pot microwave-assisted hydrothermal method and uniformly integrated into the g framework. The resulting MnCo ₂ O ₄ @g composites are designed for the sensitive and selective detection of the antibiotic CAP and toxic Pb ²⁺ heavy metal ions in aqueous media, respectively. Structural and surface characteristics of the materials are analyzed using spectroscopic techniques, confirming their superior physicochemical properties, particularly those of the MnCo ₂ O ₄ @g composites. The MnCo ₂ O ₄ @g/SPE demonstrates enhanced electrochemical characteristics, including lower charge-transfer resistance ( R _ct = 1688 Ω and Δ E _p = 190 mV), a larger electrochemically active surface area (0.1708 cm ² ), and increased density of surface-active sites. Electrochemical sensing studies reveal efficient cathodic reduction of CAP and anodic oxidation of Pb ²⁺ at MnCo ₂ O ₄ @g-based sensor. The as-developed sensor exhibits favorable electron-transfer kinetics toward the redox processes of both analytes, corresponding to the following regression equations: I _pc (μA) = 0.006 ν (mV s ⁻¹ ) + 1.529 ( R ² = 0.997) for CAP and I _pa (μA) = 3.16 ν ^1/2 (mV s ⁻¹ ) ^1/2 –2.045 ( R ² = 0.998) for Pb ²⁺ . It achieves wide linear detection ranges (0.25–50 μM for CAP, 0.5–1000 ppb for Pb ²⁺ ), low LOD of 0.2 μM for CAP and 1.07 ppb for Pb ²⁺ ), and high sensitivities (1.3 μA•μM ⁻¹ •cm ⁻² for CAP, 0.24 μA•ppb ⁻¹ •cm ⁻² for Pb ²⁺ ).